If sin(a)=x and a∈(π/2,π), find a formula for the following in terms of x:
a.) cos(a)
b.) cos(3π/2+a)
c.) tan(π+a)
sin(a) = x
a) cos(a) = sqrt(1 - sin^2(a))
= sqrt(1 - x^2)
b) cos(3π/2 + a) = -cos(π/2 + a)
= - (-sin(a))
= sina = x
c) tan(π + a) = tan(a)
= sin(a)/cos(a)
= x / sqrt(1 - x^2)